色谱 ›› 2025, Vol. 43 ›› Issue (6): 678-687.DOI: 10.3724/SP.J.1123.2024.07005

• 研究论文 • 上一篇    下一篇

基于沸石咪唑酯骨架复合微球的分散固相萃取-气相色谱-质谱法检测牛奶中18种多氯联苯

聂文丁1, 帅思婕1, 胡珂2, 崔晓垒2, 李腾飞1,*()   

  1. 1.河北工程大学生命科学与食品工程学院,河北 邯郸 056038
    2.河北省地质矿产勘查开发局 第一地质大队实验室,河北 邯郸 056000
  • 收稿日期:2024-07-03 出版日期:2025-06-08 发布日期:2025-05-21
  • 通讯作者: * E-mail:litengfei@hebeu.edu.cn.
  • 基金资助:
    河北省重点研发计划项目(22325501D)

Determination of 18 polychlorinated biphenyls in milk by dispersive solid-phase extraction based on zeolitic- imidazolate-framework composite microspheres prior to gas chromatography-mass spectrometry

NIE Wending1, SHUAI Sijie1, HU Ke2, CUI Xiaolei2, LI Tengfei1,*()   

  1. 1. School of Life Sciences and Food Engineering,Hebei University of Engineering,Handan 056038,China
    2. Laboratory of The First Geological Team,Hebei Bureau of Geology and Mineral Resources Exploration and Development,Handan 056000,China
  • Received:2024-07-03 Online:2025-06-08 Published:2025-05-21
  • Supported by:
    Key Research and Development Plan of Hebei Province, China(22325501D)

摘要:

多氯联苯(PCBs)是一类持久性有机污染物,尽管在全球范围内已被禁用,但仍以痕量水平存在于食品和环境中。PCBs残留会对人类健康和生态环境造成严重威胁,因此建立可靠的PCBs富集检测方法具有重要意义。本文以原位合成法制备壳聚糖/沸石咪唑酯骨架复合微球(CS@ZIF-8)作为分散固相萃取(DSPE)吸附剂,结合气相色谱-质谱(GC-MS),建立了一种测定牛奶中18种PCBs的分析方法。通过扫描电子显微镜、傅里叶红外光谱、X射线衍射和氮气吸附/脱附对制备的材料进行表征。考察了吸附剂用量、萃取时间、解吸时间和解吸溶剂等因素对萃取效率的影响,得到最佳萃取条件:20 mg CS@ZIF-8作为吸附剂,振荡提取30 min,1 mL正己烷超声解吸8 min。在最佳萃取条件下,18种PCBs在1~200 μg/L范围内具有良好的线性关系,相关系数(r2)均大于0.999,检出限(S/N=3)为0.06~0.24 μg/L,定量限(S/N=10)为0.19~0.79 μg/L,日内和日间精密度(n=6)分别为2.5%~5.3%和4.3%~5.9%,不同批次材料间精密度(n=3)为4.9%~9.7%。选择全脂牛奶和脱脂牛奶对本方法的适用性进行考察,在5、20和100 μg/L 3个水平下,18种PCBs的加标回收率为84.8%~114.3%。考察了CS@ZIF-8的重复利用性,经过4次吸附-解吸循环后,加标回收率仍能达到70%以上。本方法操作简便,萃取时间短,准确度高,为牛奶样品中PCBs的高效检测提供了有力支持。

关键词: 沸石咪唑酯骨架, 壳聚糖, 分散固相萃取, 气相色谱-质谱, 多氯联苯, 牛奶

Abstract:

Polychlorinated biphenyls (PCBs) are hazardous, persistent organic pollutants that are widely used industrially. Although the use of PCBs is banned in many countries, they are still present at trace levels in food and the environment. PCBs are highly chemically stable and lipophilic; hence, they are easily enriched and accumulate in the human body through milk and dairy products. PCBs residues pose serious threats to human health; therefore establishing a reliable enrichment method is an important objective. Sample pretreatment is required to efficiently extract target PCBs owing to sample-matrix complexity and their low contents. Efficient adsorbents form the cores of novel sample-pretreatment technologies, and designing new stable adsorbents is crucial for the further development of pretreatment techniques. Zeolitic imidazolate frameworks (ZIFs) are a family of metal-organic frameworks composed of imidazole linkers and metal ions. Their large surface areas, good stabilities, high porosities, and ease of modification are distinct advantages; consequently, ZIFs are widely used to adsorb organic pollutants. However, powdered ZIFs are difficult to separate and collect, which provides reuse challenges; hence, preparing ZIF composites with other functional materials is a highly effective way of addressing this challenge. Chitosan (CS) is an inexpensive and biodegradable natural polysaccharide that gelates easily. The structure of CS contains many free amino and hydroxyl groups that facilitate chemical modification and hybridization; consequently, CS is a matrix commonly used in composite materials. In this study, we prepared CS@ZIF-8 composite beads by the in-situ synthesis of ZIF-8 on chitosan through acid-solubilization/base-fixation. An analytical method for determining 18 PCBs in milk was developed using CS@ZIF-8 composite microspheres as the adsorbent for dispersive solid-phase extraction (DSPE) coupled with gas chromatography-mass spectrometry (GC-MS).The CS@ZIF-8 composite microspheres were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffractometry (XRD), and nitrogen-adsorption-desorption experiments, which confirmed that the material had been successfully prepared. How adsorbent dosage, extraction and desorption times, and type and volume of the desorption solvent affect the extraction efficiency were investigated, with the following optimal extraction conditions determined: 20 mg of CS@ZIF-8 as the adsorbent, 30 min of extraction by shaking, and 8 min of ultrasonic desorption with 1 mL of n-hexane. The 18 PCBs exhibited good linearities in the 1–200 μg/L under these optimal conditions, with coefficients of determination (r2) exceeding 0.999. Detection limits (S/N=3) ranged between 0.06 and 0.24 μg/L, with quantification limits (S/N=10) of 0.19–0.79 μg/L. Repeatability experiments were performed by the addition of 100 μg/L of the 18 PCBs, which exhibited intra-day and inter-day precisions (n=6) of 2.5%–5.3% and 4.3%–5.9%, respectively, while inter-batch material precisions (n=3) ranged between 4.9% and 9.7%. The applicability of the developed method was investigated by selecting whole milk and skim milk as samples based on PCBs lipophilicity. Spiked recovery experiments were conducted at three concentrations (5, 20, and 100 μg/L), with the 18 PCBs exhibiting spiked recoveries of 84.8%–114.3%. CS@ZIF-8 not only has a larger specific surface area than CS, but it also adsorbs PCBs through π-π interactions and hydrophobicity, leading to superior extraction efficiency. CS@ZIF-8 exhibited spiked recoveries exceeding 70% for all samples after four adsorption-desorption cycles during reproducibility testing. The developed method provides a simplified extraction process by eliminating the need for centrifugation or filtration steps that are usually associated with conventional DSPE. In addition, the developed method is highly sensitive, precise, and accurate, with adsorbent reusability a noteworthy feature, thereby supporting the simple and efficient detection of PCBs in milk samples.

Key words: zeolitic imidazolate frameworks (ZIFs), chitosan (CS), dispersive solid-phase extraction (DSPE), gas chromatography-mass spectrometry (GC-MS), polychlorinated biphenyls (PCBs), milk

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